Self-powered lights for photosynthetic cultures

ABSTRACT

Various examples of methods and systems are provided for increasing productivity of one or more photosynthetic cultures via self-powered energy output systems. In one example, a system includes a waterproof casing and an energy output module enclosed within the waterproof casing. The waterproof casing is configured to be neutrally buoyant in an enclosure comprising the one or more photosynthetic cultures. In another example, a method includes placing a self-powered energy output system within an enclosure, the self-powered energy output system being neutrally buoyant within the enclosure. The method further includes causing turbulence within the enclosure, and the self-powered energy output system harvests energy to power the self-powered energy output system via the turbulence within the enclosure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/766,189, filed Apr. 5, 2018 entitled “SELF-POWERED LIGHTS FORPHOTOSYNTHETIC CULTURES”; which is a 35 U.S.C. § 371 national stageapplication of PCT Application No. PCT/US2016/055947, filed Oct. 7,2016, where the PCT claims priority to, and the benefit of, co-pendingU.S. provisional application entitled “SELF-POWERED LIGHTS FORPHOTOSYNTHETIC CULTURES” having Ser. No. 62/238,274, filed Oct. 7, 2015,both of which are hereby incorporated by reference in their entireties.

BACKGROUND

The interest over photosynthetic microbes such as microalgae andcyanobacteria as a source of bioproducts has expanded significantly inthe last years. This interest has been promoted by the pricefluctuations and security risks associated with fossil fuels. The needto reduce costs of fuels has promoted the interest in other microalgalbioproducts that can be even more attractive economically than thebiofuels. These products can include pharmaceuticals, nutraceuticals,fertilizers, feeds, food additives, and pigments among others.

Although the microalgal productivity is higher than that of other crops,with up to 2,470-12,345 gal oil (hectare·yr)⁻¹, there are somelimitations that need to be addressed to make it competitive. One of themajor bottlenecks in the use of biofuels and other bioproducts is theavailability of light^([1-3)]. In cultures maintained outdoors, that useavailable natural light, the depth and hence the productivity of theculture is limited by the light penetration and availability in a givenarea. For cultures maintained with artificial light, the energy forillumination can be a significant part of the cost of microalgal biomassproduction, reaching in some cases 50% or more of the costs^([4-7)].Besides the light quantity, the wavelength distribution also affects themicroalgal biomass production. It has been found that the wavelengthaffects not only the biomass productivity, but also its composition.

Several strategies have been explored to reduce the cost of light andincrease the areal productivity of the microalgae. Among thesestrategies are thin layer photobioreactors, stacked reactors withwaveguides, tubular photobioreactors, submerged light strips and manyothers. None of these methods overcome the basic lighting problems: 1)for cultures using natural light, the fixed limited availability oflight energy per unit of area, the diurnal cycle (night/day) and thedepth of light penetration; and 2) for cultures with artificial light,the cost of the electrical energy to provide illumination and the lightpenetration.

SUMMARY

Embodiments of the present disclosure are related to self-powered lightsystems used for the culture of photosynthetic organisms that areconfigured to harvest energy from water movement.

In one embodiment, among others, a system for increasing productivity ofone or more photosynthetic cultures comprises a waterproof casing and alight module enclosed within the waterproof casing. The waterproofcasing is configured to be neutrally buoyant in a culture tankcomprising the one or more photosynthetic cultures.

In one or more aspects of these embodiments, the light module cancomprise a light-emitting diode (LED) and a battery, and the LED ispowered by the battery. In one or more aspects of these embodiments, thelight module can comprise an LED and a power harvesting device, and theLED is powered by the power harvesting device. In one or more aspects ofthese embodiments, the power harvesting device can comprise one or moreelectromagnetic components. In one or more aspects of these embodiments,the power harvesting device can comprise one or more piezoelectriccomponents. In one or more aspects of these embodiments, the powerharvesting device can be operable at low ambient motion frequency. Inone or more aspects of these embodiments, the power harvesting devicecan harvest energy in response to movement of the waterproof casingcaused by water turbulence in the culture tank. The water turbulence canbe caused by aeration. The water turbulence can be caused by mechanicalagitation. The water casing can be transparent. In one or more aspects,at least a portion of the light module can comprise at least one of aflorescent paint or a florescent dye.

In another embodiment, among others, a method comprises placing aself-powered light system within a culture tank, the self-powered lightsystem being neutrally buoyant within the culture tank and causingturbulence of water within the culture tank. The self-powered lightsystem harvests energy to power a light of the self-powered light systemvia the turbulence of the water within the culture tank. In one or moreaspects of these embodiments, the culture tank can comprise one or morephotosynthetic cultures. In one or more aspects of these embodiments,the light can comprise a light-emitting diode (LED), and theself-powered light system can further comprise a power harvesting devicethat is configured to harvest the energy via the turbulence of thewater.

In another embodiment, among others, a system comprises a culture tankhaving one or more photosynthetic cultures, and a self-powered lightsystem disposed within the culture tank, the self-powered light systembeing neutrally buoyant within the culture tank. In one or more aspectsof these embodiments, the self-powered light system comprises a powerharvesting device coupled to a light-emitting diode (LED) enclosed in awaterproof casing. In one or more aspects of these embodiments, thewaterproof casing can be transparent. In one or more aspects of theseembodiments, the power harvesting device comprises one or moreelectromagnetic components. In one or more aspects of these embodiments,the power harvesting device comprises one or more piezoelectriccomponents. In one or more aspects of these embodiments, the powerharvesting device harvests energy to power the LED via movement of theself-powered light system caused by at least turbulence of water withinthe culture tank. In one or more aspects of these embodiments, theturbulence of the water is caused via aeration. In one or more aspectsof these embodiments, the turbulence of the water is caused viamechanical agitation. In one or more aspects of these embodiments, atleast a portion of the self-powered light system comprises at least oneof a florescent paint or a florescent dye.

Other devices, systems, methods, features, and advantages of the presentdisclosure will be or become apparent to one with skill in the art uponexamination of the following drawings and detailed description. It isintended that all such additional devices, systems, methods, features,and advantages be included within this description, be within the scopeof the present disclosure, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views

FIG. 1 is an example of a perspective view of a light system accordingto various embodiments of the present disclosure.

FIG. 2 is an example of an expanded view of the light system of FIG. 1according to various embodiments of the present disclosure.

FIG. 3 is an example of a schematic representation of a light module ofthe light system of FIG. 1 according to various embodiments of thepresent disclosure.

FIGS. 4A and 4B are examples of schematic representations of a powerharvesting device of the light system of FIG. 1 according to variousembodiments of the present disclosure.

FIG. 4A illustrates the power harvesting device with electromagneticcomponents. FIG. 4B illustrates the power harvesting device withpiezoelectric components.

FIG. 5 illustrates an example of a schematic representation ofrectifying circuit of the light system of FIG. 1 according to variousembodiments of the present disclosure.

FIG. 6 illustrates a perspective view of an example light module of thelight system of FIG. 1 where the power source includes a batteryaccording to various embodiments of the present disclosure.

FIG. 7 illustrates a perspective view of the light system of FIG. 1disposed within a culture tank according to various embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Disclosed herein are systems and methods for a self-powered light systemused for the culture of photosynthetic organisms that are configured toharvest energy from water movement in a culture tank. Reference will nowbe made in detail to the description of the embodiments as illustratedin the drawings, wherein like reference numbers indicate like partsthroughout the several views. This disclosure is not limited toparticular embodiments described, and as such may, of course, vary. Theterminology used herein serves the purpose of describing particularembodiments only, and is not intended to be limiting, since the scope ofthe present disclosure will be limited only by the appended claims.

Where a range of values is provided, each intervening value, to thetenth of the unit of the lower limit unless the context clearly dictatesotherwise, between the upper and lower limit of that range and any otherstated or intervening value in that stated range, is encompassed withinthe disclosure. The upper and lower limits of these smaller ranges mayindependently be included in the smaller ranges and are also encompassedwithin the disclosure, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded in the disclosure.

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how toperform the methods and use the structures disclosed and claimed herein.Efforts have been made to ensure accuracy with respect to numbers (e.g.,amounts, temperature, etc.), but some errors and deviations should beaccounted for. Unless indicated otherwise, parts are parts by weight,temperature is in ° C., and pressure is at or near atmospheric. Standardtemperature and pressure are defined as 20° C. and 1 atmosphere.

Before the embodiments of the present disclosure are described indetail, it is to be understood that, unless otherwise indicated, thepresent disclosure is not limited to particular materials, reagents,reaction materials, manufacturing processes, dimensions, frequencyranges, applications, or the like, as such can vary. It is also to beunderstood that the terminology used herein is for purposes ofdescribing particular embodiments only, and is not intended to belimiting. It is also possible in the present disclosure that steps canbe executed in different sequence, where this is logically possible. Itis also possible that the embodiments of the present disclosure can beapplied to additional embodiments involving measurements beyond theexamples described herein, which are not intended to be limiting. It isfurthermore possible that the embodiments of the present disclosure canbe combined or integrated with other measurement techniques beyond theexamples described herein, which are not intended to be limiting.

It should be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a support” includes a plurality of supports. In thisspecification and in the claims that follow, reference will be made to anumber of terms that shall be defined to have the following meaningsunless a contrary intention is apparent.

While embodiments of the present disclosure are descripted in connectionwith the corresponding text and figures, there is no intent to limit thedisclosure to the embodiments in these descriptions. On the contrary,the intent is to cover all alternatives, modifications, and equivalentsincluded with the spirit and scope of embodiments of the presentdisclosure.

Convention light systems for the culture of photosynthetic organisms areknown to have the following lighting problems: 1) for cultures usingnatural light, there is fixed limited availability of light energy perunit of area, the diurnal cycle (night/day) and the depth of lightpenetration; and 2) for cultures with artificial light, there is thecost of the electrical energy to provide illumination and the lightpenetration.

The present disclosure addresses these problems through a self-poweredlight-emitting diode (LED) based neutral buoyancy light system. Thelight system of the present disclosures yields a self-powered lightsource that can be used in microalgal/cyanobacterial cultures toincrease their productivity and reduce the limitation of culture depths.The light system comprises one or more buoyant units that each integratean energy harvesting device that takes advantage of the movement neededto maintain the cultures in suspension, coupled with an efficientLED-based light that can be fine-tuned to deliver the light in thewavelength that can be more efficiently utilized by the target speciesto obtain the desired products.

Energy scavenging and harvesting from the surrounding environment canpossibly eliminate the use of battery, which reduces cost formaintenance and environmental pollution caused by discarded batteries,while enabling self-sustainable device applications such as a sensornetwork. Although a solar cell is a well-known energy harvesting device,it is not practical for the current application. As an alternative,ambient motion and vibration can be a promising and abundant source ofenergy if converted into electricity^([8]). Over the past few years,there have been research efforts in developing a small scale energyharvesting device from high frequency vibrations or resonance caused bymechanical systems or automobiles^([9,10]). Nevertheless, in real worldapplications, harvesting energy from low frequency motions is moreimportant and useful for wearable/portable electronic devices, oceanicand environmental monitoring sensor networks, and other outdoor ormilitary uses. The scavenged energy will usually be small, but can besuitable for small scale electronic sensors and low power LED lighting.

The light system of the present disclosure can harvest energy from thewater movement required to maintain the algal culture in suspension.Conventional systems depend on electricity to obtain their power, eitherin the form of rechargeable systems or directly plugged to an outlet.The self-powered lights of the present disclosure reduce the electricityconsumption for illumination to a minimum. According to variousembodiments of the present disclosure, the light sources are notattached to the culture structure, but are dispersed throughout thewhole depth of the culture. Conventional artificial lighting availableoptions either hang on top of the cultures or are submerged in fixedpositions in arrays of many lights. The dispersed, neutrally buoyantlights of the present disclosure remove the limitation of the culturedepth and can be reused continuously. Additionally, the light systemunits of the present disclosure do not require any specialinfrastructure or installation. The light system units can be used inany shape of tank, including raceways, ponds, or bioreactors.Conventional offerings must be calculated according to the geometry andcapacity of the culture system.

The light system of the present disclosure can be used for the cultureof any photosynthetic organism, such as, for example, microalgae,cyanobacteria, diatoms, filamentous algae, and/or others. Theconcentration of bioproducts of the microalgal/cyanobacterial biomasscan be manipulated through the use of lights with different wavelengthdistributions (e.g., lights around 620-700 nm or around the 400-480range can increase growth rates in some species, while in ranges ofabout 490-550 can increase the chlorophyll content). Lights of differentcolors can impact the concentration and type of pigments and lipidsproduced by microalgae^([4,6,12,13]). The light system of the presentdisclosure can be expanded to cultures in environments that have limitedor no natural light, such as, for example, closed reactors, undergroundfacilities, deep culture systems and/or other systems that cannot beaccommodated with traditional methods. In various embodiments, the lightsystem of the present disclosure can be used as the sole light system oras a complement to other illumination strategies, such as, for example,natural light, overhead light and/or others, with little to no energycost.

FIG. 1 provides an example of the light system according to variousembodiments of the present disclosure. The light system of the presentdisclosure comprises one or more units 10 comprising a light module 12disposed within enclosed in a sealed waterproof casing 14. As discussedin further detail with respect to FIG. 3, the light module 12 comprisesa power source 16 coupled to a light source 18. The casing 14 of thelight system unit 10 comprises a waterproof transparent casing sized tocontain the light module 12. The casing 14 can comprise a transparentpolymer material and/or other suitable material that is capable of beingneutrally buoyant in the microalgal cultures. The light module 12comprising the light source 18 and the power source 16 is disposedwithin the waterproof casing 14.

FIG. 2 illustrates an example of an expanded view of the light module 12disposed within the casing 14. Specifically, FIG. 12 illustrates a topportion 20 of the casing and a bottom portion 22 of the casing 14 withthe light module 12 disposed within. The top portion 20 and the bottomportion 22 are configured to connect to each other to form a sealedclosure, thereby preventing liquid from being able to enter into theinside of the sealed casing 14. In some embodiments, an adhesivematerial may be disposed around the seam connecting the top portion 20to the bottom portion 22 to further ensure that the seal is secure,eliminating the ability for liquid to enter into the inside of thesealed casing 14.

Turning now to FIG. 3, shown is an example of a schematic representationof the light module 12 according to various embodiments of the presentdisclosure. The light module 12 comprises a power source 16 coupled to alight source 18. The light source 18 can comprise a light-emitting diode(LED) and/or other suitable light source. The power source 16 cancomprise a power harvesting device 26 (FIGS. 4A-4B), a battery 28 (FIG.6), a combination of a battery and a power harvesting device, and/orother appropriate power source. In some embodiments, the light sourcecan be painted in part with fluorescent paint or dyes to adjust for thedesired wavelengths as can be appreciated.

Moving on to FIGS. 4A-4B, shown is an example of a schematicrepresentation of the power source 16 comprising the power harvestingdevice 26 according to various embodiments of the present disclosure.The power source 16 comprises a power harvesting device 26 that isconfigured to be operable at low ambient motion frequency (e.g., 0.1 Hzto 100 Hz). The power harvesting device 26 can be configured to beoperable according to an electromagnetic scavenging method (FIG. 4A), apiezoelectric power scavenging method (FIG. 4B), and/or any otherappropriate scavenging method. FIG. 4A illustrates the power harvestingdevice 26 comprising electromagnetic components 30 (e.g., genericelectromagnetic coils, Faraday electromagnetic coil, Teslaelectromagnetic coil, electrostatic electrodes, triboelectricelectrodes, etc.) and FIG. 4B illustrates the power harvesting device 26comprising piezoelectric components 32 (e.g., piezoelectric films,piezoelectric nanowires, piezoelectric nanowire forest, etc.). Usingeither the electromagnetic components 30 or the piezoelectric components32, the power harvesting device 26 is configured to generate energy frommovement of the light system unit 10 and provide power to the lightsource 18.

In some embodiments, the power harvesting device 26 includeselectromagnetic components 30 comprising a miniaturized torsion springstructure fabricated using a rapid prototyping technology and asmall-size (e.g., about 3 mm in diameter and about 1 mm in thickness)magnet, such as, for example, a Neodymium magnets (NdFeB) and/or otherappropriate rare earth magnet. The magnet can be used as the inertialmass and the magnet for electromagnetic induction. The power harvestingdevice 26 can further comprise microfabricated microcoils, a house-madecoil, an off-the-shelf miniaturized coil and/or other appropriate coil.

In some embodiments, the power harvesting device 26 is sized at about 1cm³ (1 cm×1 cm×1 cm). As the electromagnetic induction provides analternating current (AC), a simple rectifying circuit with a chargestorage device (e.g., capacitor) will be necessary to obtain a directcurrent (DC) electric power to power the light source. Since thescavenged voltage can be ultra-low, a conventional rectifying andregulating circuit may not be suitable to overcome power managementconcerns.

FIG. 5 illustrates an example of a simple rectifying circuit 34 showinga two-step voltage conversion for ultralow voltage conversion. The firststep of the two-step voltage conversion is an AC/AC voltage step-upusing a microtransformer 36 to boost the incoming AC signal 38 up toabout 500˜1,000 mV or in tenfold. The amplified signal 40 will then befed to a surface mountable electronic voltage converter circuit 42 togenerate a DC output voltage 44 that can be used to power up a lightsource 18. In some embodiments, the power source 16 comprises theharvesting device 26 and a battery 28 in combination. In someembodiments, the battery 28 can be rechargeable, and the DC outputvoltage 44 may be used to charge the battery 28 which is then used topower the light source 18.

In an experiment, a power rectifying circuit 34 with an IC (e.g.,LTC3109 from Linear Technology Corp., Milpitas, Calif.) was tested torectify a simulated AC current. The results show that the rectifyingcircuit 34 can produce an output DC voltage up to about 4.1 V with analternating AC voltage input, which is enough to turn on the lightsource 18. The fabricated device can be characterized at variousconditions of motion frequency (ambient motion) and applied acceleration(or inertial force) mimicking real world events. The power generationcan be in microwatts (μW) range, but it is possible to further improvethe power level by optimizing resonator structures and dimensions.

While the preferred embodiment of the power source 16 comprises a powerharvesting device 26 that harvests energy from related to ambient motion(e.g. movement of unit in culture tank) and/or applied acceleration(e.g., inertial force), the power source 16 can comprise a battery 28according to various embodiments. FIG. 6 illustrates a light module 12comprising a battery 28 powering a light source 18.

FIG. 7 shows an example of the light system units 10 of the presentdisclosure disposed within a culture tank 46 according to variousembodiments of the present disclosure. The culture tank 46 comprises anytype and shape of culture tank as can be appreciated, includingraceways, ponds, or bioreactors. The light system units 10 can freefloat with cultures within a culture tank 46. The movement of the waterwithin the culture tank 46 may be caused by vigorous aeration,mechanical agitation (e.g., paddles), and/or other suitable method toproduce appropriate turbulence for algal cultures. As the light systemunit moves in response to the movement of the water, the power source 16generates the energy, via the ambient energy of the unit, used to powerthe light source 18.

It has been well documented that the type and intensity of light affectsthe growth and composition of the microalgal/cyanobacterial cultures. Totest the effect of the suspended light system units 10 of the presentdisclosure, a microalgal and cyanobacterial species of interest can beinoculated in the culture tank 46, to an optical density of 0.1. Theculture can be maintained in Bold's Basal medium^([14]) until theoptical density reaches a plateau. The growth rate can be estimatedbased on the optical density. A calibration curve of optical density vsdry biomass can be prepared to estimate the biomass increase with time.Pigment content (Chlorophyll or phycocyanin, depending on the speciesselected) can be measured by spectrophotometric and/or fluorescencemethods. The biomass and lipid productivity can be estimated. The effectof the biomass density on the light distribution and intensity can bemeasured. The results of this task can indicate, as appreciated, thenumber and intensity of suspended lights needed, based in the culturedensity and growth rate. Optical density can be measured with aspectrophotometer at a wavelength of 640 nm (HACH 6000). Nutrients canbe measured with spectrophotometric methods (HACH 6000). The pH,temperature, and ORP can be measured with a probe (HACH).

It should be noted that ratios, concentrations, amounts, and othernumerical data may be expressed herein in a range format. It is to beunderstood that such a range format is used for convenience and brevity,and thus, should be interpreted in a flexible manner to include not onlythe numerical values explicitly recited as the limits of the range, butalso to include all the individual numerical values or sub-rangesencompassed within that range as if each numerical value and sub-rangeis explicitly recited. To illustrate, a concentration range of “about0.1% to about 5%” should be interpreted to include not only theexplicitly recited concentration of about 0.1 wt % to about 5 wt %, butalso include individual concentrations (e.g., 1%, 2%, 3%, and 4%) andthe sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within theindicated range. In an embodiment, the term “about” can includetraditional rounding according to significant figures of the numericalvalue. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ toabout ‘y’”.

While only a few embodiments of the present disclosure have been shownand described herein, it will become apparent to those skilled in theart that various modifications and changes can be made in the presentdisclosure without departing from the spirit and scope of the presentdisclosure. All such modification and changes coming within the scope ofthe appended claims are intended to be carried out thereby.

REFERENCES

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We claim at least the following:
 1. A system, comprising: a waterproofcasing that is neutrally buoyant; and an energy output source enclosedwithin the waterproof casing, the energy output source being powered inresponse to movement of the waterproof casing.
 2. The system of claim 1,further comprising a power harvesting device coupled to the energyoutput source.
 3. The system of claim 2, wherein the power harvestingdevice is operable at low ambient motion frequency.
 4. The system ofclaim 2, wherein the power harvesting device comprises one or moreelectromagnetic components.
 5. The system of claim 2, wherein the powerharvesting device comprises one or more piezoelectric components.
 6. Thesystem of claim 2, wherein the power harvesting device harvests energyin response to the movement of the waterproof casing.
 7. The system ofclaim 1, wherein the movement is caused by aeration associated with anambient environment of the waterproof casing.
 8. The system of claim 1,wherein the movement is caused by mechanical agitation associated withan ambient environment of the waterproof casing.
 9. The system of claim1, further comprising a container comprising the one or more of the oneor more photosynthetic cultures.
 10. The system of claim 1, wherein thewaterproof casing is transparent.
 11. The system of claim 1, wherein atleast a portion of the energy output source comprises at least one of aflorescent paint or a florescent dye.
 12. A method, comprising, placinga self-powered energy output system within a container, the self-poweredenergy output system being neutrally buoyant within the container; andcausing turbulence within the container, wherein the self-powered energyoutput system harvests energy to power the self-powered energy outputsystem via the turbulence within the container.
 13. The method of claim12, wherein the container comprises one or more photosynthetic cultures.14. The method of claim 12, wherein the self-powered energy outputsystem further comprises a power harvesting device that is configured toharvest the energy via the turbulence within the container.
 15. Asystem, comprising: an enclosure comprising one or more photosyntheticcultures; and a self-powered energy output system disposed within anenclosure, the self-powered energy output system being neutrally buoyantwithin the enclosure.
 16. The system of claim 15, wherein theself-powered energy output system comprises a power harvesting devicecoupled to a light source enclosed in a waterproof casing.
 17. Thesystem of claim 16, wherein the power harvesting device comprises atleast one of: one or more electromagnetic components or one or morepiezoelectric components.
 18. The system of claim 16, wherein the powerharvesting device harvests energy to power the light source via movementof the self-powered energy output system caused by at least turbulencewithin the enclosure.
 19. The system of claim 18, wherein the turbulenceis caused via aeration or mechanical agitation.
 20. The system of claim15, wherein at least a portion of the self-powered energy output systemcomprises at least one of a florescent paint or a florescent dye.